#1529 Adds logging suppression to Broadcaster to limit total logged e…

…rror messages. (#1530)

Co-authored-by: Dennis Sheirer <dsheirer@github.com>

src/main/java/io/github/dsheirer/log/LoggingSuppressor.java

@@ -0,0 +1,139 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2023 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.log;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.slf4j.Logger;
+
+/**
+ * Logging suppressor that squelches log messages after they have been logged and continue to occur.
+ */
+public class LoggingSuppressor
+{
+    private Map<String,Integer> mSuppressionCountMap = new HashMap<>();
+    private Logger mLogger;
+
+    /**
+     * Constructs an instance
+     * @param logger to receive suppressed log messages.
+     */
+    public LoggingSuppressor(Logger logger)
+    {
+        mLogger = logger;
+    }
+
+    /**
+     * Logs the information message.
+     * @param key for suppression.
+     * @param maxCount of the logged instance.
+     * @param message to log.
+     */
+    public void info(String key, int maxCount, String message)
+    {
+        if(canLog(key, maxCount))
+        {
+            mLogger.info(message + getTag(key, maxCount));
+        }
+    }
+
+    /**
+     * Logs the information message.
+     * @param key for suppression.
+     * @param maxCount of the logged instance.
+     * @param message to log.
+     * @param t stack trace to include.
+     */
+    public void info(String key, int maxCount, String message, Throwable t)
+    {
+        if(canLog(key, maxCount))
+        {
+            mLogger.info(message + getTag(key, maxCount), t);
+        }
+    }
+
+    /**
+     * Logs the error message.
+     * @param key for suppression.
+     * @param maxCount of the logged instance.
+     * @param message to log.
+     */
+    public void error(String key, int maxCount, String message)
+    {
+        if(canLog(key, maxCount))
+        {
+            mLogger.error(message + getTag(key, maxCount));
+        }
+    }
+
+    /**
+     * Logs the error message.
+     * @param key for suppression.
+     * @param maxCount of the logged instance.
+     * @param message to log.
+     * @param t stack trace to include.
+     */
+    public void error(String key, int maxCount, String message, Throwable t)
+    {
+        if(canLog(key, maxCount))
+        {
+            mLogger.error(message + getTag(key, maxCount), t);
+        }
+    }
+
+    /**
+     * Creates a logging tag that logs the suppression statistics.
+     * @param key for retrieving current count.
+     * @param maxCount to log.
+     * @return logging tag
+     */
+    private String getTag(String key, int maxCount)
+    {
+        int count = mSuppressionCountMap.get(key);
+        return " [Log Suppress " + count + "/" + maxCount + "]";
+    }
+
+    /**
+     * Indicates if the operation can be logged without exceeding the max logging count specified by the user.
+     * @param key for tracking by count
+     * @param maxCount of the key to log
+     * @return true if can log or false.
+     */
+    private boolean canLog(String key, int maxCount)
+    {
+        if(mSuppressionCountMap.containsKey(key))
+        {
+            int count = mSuppressionCountMap.get(key);
+
+            if(count >= maxCount)
+            {
+                return false;
+            }
+
+            mSuppressionCountMap.put(key, count + 1);
+        }
+        else
+        {
+            mSuppressionCountMap.put(key, 1);
+        }
+
+        return true;
+    }
+}

src/main/java/io/github/dsheirer/sample/Broadcaster.java

@@ -18,22 +18,26 @@
  */
 package io.github.dsheirer.sample;
 
+import io.github.dsheirer.log.LoggingSuppressor;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
-import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
  * Broadcasts an item to multiple listeners
  */
 public class Broadcaster<T> implements Listener<T>
 {
-    private final static Logger mLog = LoggerFactory.getLogger(Broadcaster.class);
+    private static LoggingSuppressor sLoggingSuppressor;
     private List<Listener<T>> mListeners = new CopyOnWriteArrayList<>();
 
+    /**
+     * Constructs an instance
+     */
     public Broadcaster()
     {
+        sLoggingSuppressor = new LoggingSuppressor(LoggerFactory.getLogger(Broadcaster.class));
     }
 
     /**
@@ -117,16 +121,25 @@ public void clear()
      */
     public void broadcast(T t)
     {
-        try
+        for(Listener<T> listener: mListeners)
         {
-            for(Listener<T> listener: mListeners)
+            try
             {
                 listener.receive(t);
             }
-        }
-        catch(Exception e)
-        {
-            mLog.error("Error while broadcasting [" + t.getClass() + "] to listeners");
+            catch(Exception e)
+            {
+                if(t != null)
+                {
+                    sLoggingSuppressor.error(t.getClass().toGenericString(), 5,
+                    "Error while broadcasting [" + t.getClass() + "] to listeners", e);
+                }
+                else
+                {
+                    sLoggingSuppressor.error("null broadcast object", 5, "Can't broadcast null " +
+                            "object to listener [" + listener.getClass() + "]", e);
+                }
+            }
         }
     }
 }